Valve-tappet compensator



Oct. 1 19 1 27 R. LEE

VALVE TAPPET COMPENSATOR Filed Feb. 25. 1922 Z Z a a o 1 32 r G fl G S n\ 5 w: m I EEE O y a F a m g i m v 1 2 mm 6 la'tented Oct. 11, 19 27.

UNITED STAT S PATENT OFFICE.

ROYAL LEE, or MILWA KEE; wIscoNsIN, ASSIGNOB T0 LEE ENGINEERING RESEARCH CORPORATION, or MILWAUK E, WISCONSIN, A CORPORATION or WISCONSIN.

VALVE-TAPPET COMPENSATOB.

Application filed February 25, 1922. Serial No. 539,150.. I

This invention has for its object toprovide a compensator for the valve tappets of gas engines whereby the variation 1n length of the valve stem or valve rod will eflect a compensating variation in length of the tappet whereby lost motion will be avoided with its accompanying objectionable fea tures such as the variation of period and timing of the valveopening and-the noise and Wear of the loose parts. v

It is a well known fact that, with the usual valve operating mechanism employed in gas ."engine construction wherein a tappet is engaged by a cam on the cam shaft and is lifted to lift in turn the valve stem or a valve rod connected with a valve-stem by means of a rocker arm, more or less play or lost motion is unavoidable and without,.frequent adjustment, which is sometimes ditficult of accomplishment and more diiiicult to maintain, this play or lost motion increases with a corresponding increase in the noise of operation caused by the hammering of the parts and a loss of efiic-iency due to a reduced valve opening period and a variation in the timing of the valve opening movement. Too close an adjustment has to be avoided as it will serve to prevent the valve from seating, especially when the parts are lengthened by the expansion due tovheat,

and it is usual for manufacturers to caution customers to adjust the tappets only when the engine is hot and then allow a clearance orplay between the parts. Such play or clearance will then become greater when the engine is cool with a corresponding'decrease in efficiency and increase in noise of operation. I

- The present invention provides a tappet capable of self elongation and contraction by hydraulic jack action to maintain the parts in touch and so prevent play or lost motion and still not cause the valve to be held off of its seat.

,VVith the above and other objects in view the invention consists in the valve tappet compensator as. herein 'claimed and all equivalents.

Referring to the accompanying drawings, in which like characters of'reference indicate the same parts in different views,

Fig. 1 is a sectional view of a gas engine valve provided with a tappet compensator of this invention; y I

Fig. 2 isan enlarged sectional viewof the tappet on a lane at ri ht an les to that of Fig. 1, and g Fig. 3 is a sectional of Fig. 1.

In thesedrawings 10 indicates the engine casing having the usual tappet valve 11 with Its stem 12 passing through the guide or view on the line 33 bushing 13 and forced by a surrounding valve spring l t in the direction for closing the valve. "While, for convenience, that type of valve having its stem directly engaged by the tappet is shown, it will be understood that the lnventlon is equally applicable to the type of valve'havi-ng a valve rod engaged by the tappet and connected with the valve stem by means of a rocker arm and, throughout the description and claims wherever the valve stem is referred to,.it will be understood that the valve rod of such other valves is also meant.

.The cam 15 on the cam shaft 16 engages the end of a tappet member 17 in. the usual manner'to force it against the end of the valve stem 12. The tappet member 17 is slldably fitted in a guide bushing 18 in the usual manner, but, instead of merely being provided with adjusting screw'and set nutas usual, it has combined with its adjustment features the feature of self-elongation or contraction before'mentioned. The tappet memberl? constitutes a cylinder in which is slidably mounted a hollow plunger 19 containing an oil Well 20 with a supply of oil. A cross-pin 2l :passes through the cylinder 17 and through slots 22 in the walls of the plunger 19 to afford a spring seat without interfering withthe slidmg movement of the plunger. 'Adjustably threaded in the end of the plunger is a screw plug 23, whlch bears on the end ofthe valverod, or valve stem as the case may be, and j is locked in its adjustment by a set nut 24;

thereon bearing on the flanged end of the plunger 19. Bearing on this screw'plug 23 and preferably contained Within a cavity in its end is a coiled spring 25, which may be centered by a guide pin 26 with pne end fitting in a reduced bore of the screw plug 23 and the other end fitting in an opening The parts are so designed that the spring tends to lift the plunger 19 as far as Wlll be permitted or'untll the screw plug 23 engages the valve stem or valve rod and maintains it in touch therewith at all times, though of course the spring 25 is inferior to the valve spring 14 and cannot obstruct the closing of the valve. The fit of the plunger 19 in the cylinder 17 is reasonablytight and the upward movement of the plunger with respect to the cylinder is accompanied by an outflow of oil from the oil well through a passage 28 controlled by a check valve of anysuitable type, in this'instance a spring reed fastened to the end of the plunger. The oil that passes through the passageway 28 into the space between the cylinder end and the plunger cannot return through said passage because. of the check valve 29 andconsequently the elongation of the. tappet by the relative. movement between the plunger and cylinder is maintained so that the valve will receive the full throw of the cam. Repeated operations, during which the tappet is subjected to, considerable pressure, will efl'ect a very slow leakage of oil around the plunger until the openings' 22 are reached, through which itis re-.

turned to the oil well, and it is this slow bleeding or leakage that is relied on for permitting the tappet to contract as the other parts elongate and so avoid holding the valve ofi of its'seat, though not permitting play 'or lost motion. Should the bleedingallow of contraction of the tappet greater thannecessary for this purpose, the least tendencyto play will permit the spring 25 to slightly lift the plunger with respect to the cylinder and so permit sufiicient oil to pass the check valve to restore the tappet to the length necessary for making a'close fit between the cam and the valve stem or valve rod. The expert;

sion of the parts is gradual, so that the tap,- pet may easily keep pace therewith in its I self-elongation or contraction.

Should it become necessary to replenish the supply of oil in the oil well from time to time, it IS only necessary to inject oil from an oil can into the plunger, after removing the screw plug 23, preferably at times when the valves are reground and the valve springs are released for that. purpose. Should the supply of oil become exhausted or, for any other reason, the hydraulic jackprinciple fail, the tappet may only be compressed by the action of the cam to an extent that is at present allowed for the play betweenthe tappet and the valve rod forthis is the distance that is allowed when adjustin the screw plug 23 while the flange or stop 0 plunger 19 bears on the end of cylinder 17. That distance will, of course, vary as the effective length of the tappet varies to compensate for contraction and expansion of other parts, but the point now made is that a failure of the hydraulic jack will only allow that amount of play which is now customary and which may be determined by the adjustment of screw plug 23.

The use of tappets according to the present invention serves to eliminate the valve noises and the loss of efliciency in wear caused by excessive play or lost motion and still the tappet contains its compensating mechanism within itself so that it may readily replace the ordinary tappets.

The internal spring arrangement shown is preferred, though obviously an external spring may be substituted so long as it tends to separate the plunger and the cylinder.

l/Vhile the tappet compensator is herein shown as embodied in the tappet member itself, it will be understood that it may be located anywhere in the line of communication between the tappet member and the valve. v

What I claim as new and desire to secure by Letters Patent is: I

1. A valve tappet comprising a cylinder forming a tappet member, a plunger working therein and containing an oil well having check valve controlled communication with the space between the plunger and the cylinder, an adjusting screw threaded in the plunger for engaging the valve stem, a cross pin extending through the cylinder without interfering with movements of the plunger, and a spring bearing on the cross pin and the adjusting screw and tending to separate the plunger and the cylinder.

2. A valve tappet comprising a slidably mounted cylinder forming a tappet engaged by the cam, a plunger working therein and provided with a central bore forming an oil well with a check valve controlled communication with the :'space between the plunger and the cylinder, an adjusting screw threaded in the bore of the cylinder for engaging the valve stem, there being atransverse opening through theplunger, a cross pin passing through the cylinder and freely contained within the transverse opening of the plunger without interfering with the plunger movements, a guide pin fitting in the cross pin 

